CN113303854A

CN113303854A - Suture reload assembly with detachable knife

Info

Publication number: CN113303854A
Application number: CN202110182992.4A
Authority: CN
Inventors: 贾斯汀·威廉斯; 拉塞尔·普里巴尼奇; 戴维·A·尼古拉斯
Original assignee: Covidien LP
Current assignee: Covidien LP
Priority date: 2020-02-26
Filing date: 2021-02-08
Publication date: 2021-08-27
Anticipated expiration: 2041-02-08
Also published as: US20210259694A1; US11779343B2; EP3871616B1; EP3871616A1; CN113303854B

Abstract

A surgical stapling device includes an anvil assembly and a reload assembly including a knife and a knife carriage. The knife is removably coupled to the knife block and is embedded in a cutting loop of the anvil assembly when the stapling apparatus is fired. The knife may be separated from the blade holder after the predetermined force is applied to the knife. The predetermined force is applied to the knife after firing the stapling apparatus by moving the anvil assembly relative to the reload assembly from a clamped position to an open position.

Description

Suture reload assembly with detachable knife

Cross Reference to Related Applications

The benefit and priority of united states provisional patent application No. 62/981,636, filed on 26.2.2020, this application is hereby incorporated by reference in its entirety.

Technical Field

The present disclosure relates generally to surgical stapling devices and, more particularly, to circular surgical stapling devices that include a knife for cutting tissue.

Background

Circular stapling devices typically include a housing or reload assembly having a staple cartridge, a staple pusher and an annular knife. The staple cartridge supports one or more annular rows of staples, and a staple pusher is movable within the staple cartridge to eject the staples from the staple cartridge. The annular knife is positioned radially inward of the annular row of staples and is movable from a retracted position to an advanced position to cut or core tissue. The annular knife may move synchronously with the staple pusher or may move independently of the staple pusher to cut tissue during a surgical procedure, such as an anastomosis procedure.

During an anastomosis procedure, two tubular tissue slices are joined to one another and the tissue within the tubular slices is cored with a knife to define a hollow channel between the joined tubular slices. Generally, after the tissue section is cut, the tissue ring is retained within the annular knife of the reload assembly. When the reload assembly is removed from the patient, the clinician removes the ring of tissue from within the annular knife.

After actuation of the circular stapling apparatus to cut tissue during an anastomosis procedure, the knife is moved from an advanced position in which the cutting edge of the annular knife is exposed to a retracted position in which the cutting edge of the knife is recessed and shielded within the staple cartridge of the reload assembly. During removal of the ring of tissue from within the annular knife, the cutting edge of the knife is pulled in a distal direction, which may inadvertently expose the cutting edge of the knife. Exposure of the cutting edge of the knife poses a risk to the clinician operating the stapling device.

Disclosure of Invention

The technology of the present disclosure generally relates to circular stapling devices having a knife for cutting tissue. In aspects of the present disclosure, a housing stapling device includes an anvil assembly and a reload assembly including a knife and knife carriage. A knife is removably coupled to the knife block and is embedded in the cutting ring of the anvil assembly when the stapling apparatus is fired. The knife may be separated from the blade holder after the predetermined force is applied to the knife. The predetermined force is applied to the knife after firing the stapling apparatus by moving the anvil assembly relative to the reload assembly from the clamped position to the open position.

One aspect of the present disclosure is directed to a reload assembly comprising a housing, a staple cartridge, a staple pushing member, a knife block, and a knife. The housing shell defines a cavity and has a proximal portion and a distal portion. The staple cartridge is supported on the distal portion of the housing shell and supports a plurality of staples. The staple pushing member is movable within the housing shell between an advanced position and a retracted position to eject a plurality of staples from the staple cartridge. The staple pushing member defines a longitudinal bore. A blade carrier is supported within the longitudinal bore of the staple pushing member and has a distal portion defining a first engagement portion. The tool holder is movable within the housing between a retracted position and an advanced position. The cutter has a proximal portion and a distal portion. The proximal portion defines a second engagement portion coupled to the first engagement portion to removably secure the knife to the knife holder. The knife may be uncoupled from the first engagement portion of the knife holder upon application of the predetermined force to the knife in the distal direction.

In aspects of the present disclosure, the knife is annular.

In some aspects of the present disclosure, the first engagement portion is defined by a plurality of resilient fingers formed on a distal portion of the blade carrier.

In certain aspects of the present disclosure, each of the plurality of resilient fingers defines a concave surface to define an annular recess surrounding the distal portion of the tool holder.

In aspects of the present disclosure, the second engagement portion is formed on the proximal portion of the knife and includes an annular projection that is received within an annular recess defined by a plurality of resilient fingers of the knife holder to removably secure the knife to the knife holder.

In aspects of the present disclosure, a second engagement portion is formed on a proximal portion of a knife by inverting the proximal portion of the knife.

Another aspect of the present disclosure is directed to a stapling apparatus that includes an adapter assembly, a reload assembly, and an anvil assembly. The adapter assembly has a distal tip portion. A reload assembly is secured to the distal tip portion of the adapter assembly and comprises a housing shell, a cartridge assembly, a staple pushing member, a knife carriage, and a knife. The housing shell defines a cavity and has a proximal portion and a distal portion. The staple cartridge is supported on the distal portion of the housing shell and supports a plurality of staples. The staple pushing member is movable within the housing shell between an advanced position and a retracted position to eject a plurality of staples from the staple cartridge. The staple pushing member defines a longitudinal bore. A blade carrier is supported within the longitudinal bore of the staple pushing member and has a distal portion defining a first engagement portion. The knife carriage moves within the housing between a retracted position and an advanced position. The cutter has a proximal portion and a distal portion. The distal portion defines a cutting edge. The proximal portion defines a second engagement portion coupled to the first engagement portion to removably secure the knife to the knife holder. The knife may be uncoupled from the first engagement portion of the knife holder upon application of the predetermined force to the knife in the distal direction. The anvil assembly is movable relative to the staple cartridge between an open position and a clamped position and includes a cutting loop formed of a material penetrable by the knife. The knife is embedded in the cutting ring when the stapling device is fired, and the knife is separated from the knife block after the stapling device is fired when the anvil assembly is moved from the clamped position to the open position.

Another aspect of the present disclosure is directed to a knife assembly comprising a knife holder and a knife. The tool holder has a distal portion defining a first engagement portion. The cutter has a proximal portion and a distal portion. The distal portion defines a cutting edge. The proximal portion defines a second engagement portion coupled to the first engagement portion to removably secure the knife to the knife holder. The knife may be uncoupled from the first engagement portion of the blade holder after the predetermined force is applied to the knife.

The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.

Drawings

Various aspects and features of the disclosure are described with reference to the drawings, wherein like reference numerals designate identical or corresponding elements in each of the several views, and:

FIG. 1 is a side perspective view of a surgical stapling device incorporating a tool assembly having a reload assembly in accordance with aspects of the present disclosure;

FIG. 2 is an enlarged view of a distal portion of the surgical stapling apparatus shown in FIG. 1 with the anvil assembly removed;

FIG. 3 is a side perspective exploded view of a reload assembly of the surgical stapling apparatus of FIG. 1;

FIG. 4 is an enlarged view of the designated detail area shown in FIG. 3;

FIG. 5 is a side perspective view of the knife holder and annular knife of the surgical stapling device shown in FIG. 3;

FIG. 6 is a cross-sectional view of the annular knife separated from the knife holder, taken along section line 6-6 of FIG. 4;

FIG. 7 is a cross-sectional view through the tool holder and a distal portion of the annular knife as the annular knife is moved into engagement with the tool holder;

FIG. 8 is a cross-sectional view through the tool holder and a distal portion of the annular knife with the annular knife engaged with the tool holder;

FIG. 9 is a cross-sectional view through the tool holder and the distal portion of the annular knife with the annular knife engaged with the tool holder;

FIG. 10 is a cross-sectional view taken along section line 10-10 of FIG. 2, with the surgical stapling apparatus in a clamped position;

FIG. 11 is a cross-sectional view taken along section line 11-11 of FIG. 2, with the surgical stapling apparatus in a clamped and fired position;

FIG. 12 is a cross-sectional view taken along section line 11-11 of FIG. 2, wherein the surgical stapling apparatus is in a fired position when moved toward an undamped position;

FIG. 13 is a cross-sectional view taken along section line 11-11 of FIG. 2 after the surgical stapling device has been fired when the surgical stapling device is moved to the undamped position and the annular knife is separated from the knife carriage;

FIG. 14 is a cross-sectional view of the distal portion of the surgical stapling device illustrated in FIG. 1, with the surgical stapling device in a fired, undamped position, with the anvil assembly in a tilted position, and with the annular knife separated from the knife block; and

FIG. 15 is a side perspective view of the distal portion of the surgical stapling device illustrated in FIG. 14 with the surgical stapling device in an undamped, fired position and with the annular knife separated from the knife block.

Detailed Description

The disclosed surgical stapling devices incorporating a reload assembly incorporating various aspects of the present disclosure will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the disclosed aspects are merely examples of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Further, directional terms such as anterior, posterior, superior, inferior, top, bottom, distal, proximal, and the like are used to aid in understanding the description and are not intended to limit the present disclosure.

In this description, the term "proximal" is generally used to refer to the portion of the device that is closer to the clinician, while the term "distal" is generally used to refer to the portion of the device that is farther from the clinician. In addition, the term "clinician" is commonly used to refer to medical personnel, including doctors, nurses, and support staff.

The present disclosure relates to a circular surgical stapling device including a reload assembly having a knife carriage removably coupled to a knife having a cutting edge and separable from the knife carriage upon application of a predetermined force to the knife. A knife is positioned to engage and penetrate a cut ring assembly on an anvil assembly of the stapling device when the stapling device is fired. The engagement of the knife with the cut ring assembly is sufficient to separate the knife from the knife block when the knife block is returned to the retracted position after the stapling apparatus has been fired. When the knife is separated from the knife holder, the cutting edge of the knife is embedded in the cut ring assembly to avoid exposing the cutting edge of the knife to the clinician.

FIG. 1 illustrates a circular stapling device 10 including a reload assembly, shown generally as reload assembly 100, according to aspects of the present disclosure. Circular stapling apparatus 10 includes a handle or actuator assembly 12, an elongated body or adapter assembly 14, a reload assembly 100 and an anvil assembly 18 supported for movement relative to reload assembly 100 between an undamped position and a clamped position (fig. 10). In aspects of the present disclosure, the reload assembly 100 comprises a proximal portion 102 detachably coupled to a distal portion of the adapter assembly 14, and the adapter assembly 14 comprises a proximal portion detachably coupled to the handle assembly 12. Alternatively, it is contemplated that the reload assembly 100 may be fixedly secured to the adapter assembly 14 and/or the adapter assembly may be fixedly secured to the handle assembly 12. Handle assembly 12 includes a body 22 defining a stationary handle 22a supporting an actuation button 24 for controlling the operation of the various functions of circular stapling apparatus 10, including accessing reload assembly 100 and anvil assembly 18, firing staples from reload assembly 100, and cutting or coring tissue, as described in further detail below.

The circular stapling apparatus 10 is illustrated as a powered stapling apparatus that includes a powered handle assembly 12 that may support one or more batteries (not shown). The adapter assembly 14 transfers power from the handle assembly 12 to the reload assembly 100 and the anvil assembly 18, respectively, for stapling and cutting tissue. Examples of electrically powered suturing devices can be found in U.S. patent nos. 9,055,943 and 9,023,014 and 2018/0125495 and 2017/0340351. Alternatively, it is contemplated that aspects of the reload assembly 100 disclosed herein may also be incorporated into a manual stapling device such as that disclosed in U.S. Pat. No. 7,303,106 (the' 106 patent) or a stapling device configured for use with a robotic system and not including a handle assembly such as that disclosed in U.S. Pat. No. 9,962,159.

Fig. 2 and 3 illustrate a reload assembly 100 comprising a housing 110, a staple actuator 112, a staple pushing member 112a, a knife block 114, an annular knife 116 supported on knife block 114, a staple cartridge 118, and a plurality of staples 120 supported within staple cartridge 118. The outer housing 110 includes an outer housing section 121 and an inner housing section 122 spaced apart from one another to define an annular cavity 124. The staple actuator 112 and staple pushing member 112a are movable within the annular cavity 124 of the housing shell 110 from a retracted position to an advanced position to eject the staples 120 from the staple cartridge 118.

Staple cartridge 118 is annular and defines an annular row of staple pockets 126. Each staple pocket 126 supports one of the staples 120. The staple actuator 112 and the staple pushing member 112a define a longitudinal through bore 128 (FIG. 10) that receives the knife block 114. The staple actuator 112 has a distal portion that abuts a proximal portion of the staple pushing member 112a such that distal movement of the staple actuator 112 within the housing shell 110 causes distal movement of the staple pushing member 112a within the housing shell 110. The staple pushing member 112a of the reload assembly 100 has a plurality of fingers 130 (fig. 3). Each of the plurality of fingers 130 is received within a respective one of the staple recesses 126 of the staple cartridge 118 and is movable through the respective staple recess 126 to eject the staple 120 from the staple recess 126 as the staple pushing member 112a moves within the housing shell 110 from the retracted position (fig. 10) to the advanced position (fig. 11).

The knife block 114 is received within the longitudinal throughbore 128 of the staple actuator 112 and includes a distal portion 140 and a plurality of spaced apart longitudinally extending proximal portions 142 (FIG. 3). The distal portion 140 and the proximal portion 142 define a stepped central bore that receives the inner housing portion 122 (fig. 3) of the housing 110 such that the knife block 114 is movable within the staple actuator 112 about the inner housing portion 122 of the housing 110 between a retracted position (fig. 10) and an advanced position (fig. 11). Proximal portion 142 of cartridge 114 defines a slot 148 that receives guide portion 110a of housing shell 110 to limit cartridge 114 to longitudinal movement within housing shell 110.

The housing shell 110 includes a proximal portion 158 that supports a coupling mechanism 160 (FIG. 3) that removably couples the reload assembly 100 to the adapter assembly 14 of the suturing device 10 (FIG. 1) to facilitate replacement of the reload assembly 100 and reuse of the suturing device 10. The coupling mechanism 160 includes a retaining member 162 and a coupling member 164. The retaining member 162 secures the coupling member 164 about the proximal portion 158 of the housing shell 110. The coupling member 164 is received around the proximal portion 158 of the housing shell 110 and engages the distal portion 14a (fig. 1) of the adapter assembly 14 to couple the adapter assembly 14 to the reload assembly 100. It is contemplated that other coupling mechanisms may be used to secure the reload assembly 100 to the adapter 14.

Fig. 4-6 illustrate distal portion 140 of tool holder 114 and annular knife 116 of reload assembly 100. Distal portion 140 of tool holder 114 is generally cylindrical and contains a reduced diameter region 170. In aspects of the present disclosure, the reduced diameter region 170 is defined in part by a plurality of resilient fingers or detents 172. Each of the plurality of resilient fingers 172 includes an engagement portion 174 that removably engages the annular knife 116 to secure the annular knife 116 to the knife block 114. In certain aspects of the present disclosure, engagement portion 174 of each of resilient fingers 172 defines an outwardly facing concave surface 174a such that reduced diameter region 170 on distal portion 140 of tool holder 114 defines an annular recess.

The annular knife 116 includes a body 180 having an annular cutting edge 182 at its distal end and an engagement portion 184 on its proximal end portion. In aspects of the present disclosure, engagement portion 184 on the proximal end of annular knife 116 includes an annular or substantially annular projection 186 (fig. 6) that is received within the annular recess defined by engagement portions 174 of resilient fingers 172 to removably secure annular knife 116 to distal portion 140 of cartridge 114. In certain aspects of the present disclosure, the engagement portion 184 on the proximal end portion of the annular knife 116 is formed by crimping or inverting the proximal end portion of the annular knife 116 inwardly upon itself.

Fig. 7-9 illustrate the annular knife 116 when the annular knife 116 is coupled to the distal portion 140 of the knife holder 114. To couple the annular knife 116 to the knife holder 114, the proximal end portion of the annular knife 116 is aligned with the distal portion 140 of the knife holder 114, and the annular knife 116 is moved toward the knife holder 114 in the direction indicated by arrow "a" in fig. 7. When the engagement portion 184 on the proximal end portion of the annular knife 116 engages the resilient fingers 172 on the distal portion 184 of the knife holder 114, the resilient fingers 172 deform inwardly in the direction indicated by arrow "B" in fig. 7 to allow the engagement portion 184 on the proximal end of the annular knife 116 to pass over the resilient fingers 172 and into the annular recess defined by the concave surfaces 174a of the resilient fingers 172. When the engagement portion 184 of the annular knife 116 passes over the resilient fingers 172 and into the annular recess defined by the resilient fingers 172, the resilient fingers 172 return to their undeformed position in the direction of arrow "C" in fig. 8 to retain the annular knife 116 on the distal portion of the knife holder 114. The annular knife 116 will remain on the distal portion of the knife holder 114 until a predetermined force is applied to the annular knife 116 that is sufficient to disengage the engagement portion 184 on the proximal end of the annular knife 116 from within the annular recess defined by the concave surfaces 174a of the resilient fingers 172. The predetermined force may be set to a desired level by selecting the material used to form fingers 172 of tool holder 114 with a suitable elasticity and/or thickness.

It is contemplated that the engagement portions of tool holder 114 and annular knife 116 may have a variety of different configurations not shown herein for removably coupling annular knife 116 with tool holder 114. It is also contemplated that the engagement portions of the annular knife 116 and the knife block 114 may be configured as interlocking devices, via a friction and/or breaking operation.

FIG. 10 illustrates the reload assembly 100 and anvil assembly 18 of the stapling device 10 in a clamped, unfired position with the staple actuator 112, staple pushing member 112a, knife block 114 and annular knife 116 in their retracted positions and the anvil assembly 18 in juxtaposed alignment with the staple cartridge 118. In this position, annular cutting edge 182 is recessed within staple cartridge 118.

As illustrated, anvil assembly 18 includes an anvil head 30 pivotally supported on a center rod 32. Anvil head 30 is pivotable on center rod 32 from an operating position (fig. 10) to a tilted or reduced profile position (fig. 14). For a description of the operation of exemplary aspects of an anvil assembly including a tiltable anvil head, see the' 106 patent. Anvil head 30 supports a cut ring assembly 40 that includes a cut ring 42 aligned with a cutting edge 182 of knife 116. The cutting ring 42 is formed of a material that is penetrable by a cutting edge 182 of the knife 116 when the knife 116 is advanced into the cutting ring 42 when the stapling device 10 (FIG. 1) is fired.

FIG. 11 illustrates the reload assembly 100 and anvil assembly 18 of the stapling apparatus 10 in the clamped and fired position. In this position, staple actuator 112 and staple pushing member 112a have been moved in the direction indicated by arrow "D" to an advanced position to eject staples 120 from staple cartridge 118 into anvil head 30. In addition, knife block 114 and annular knife 116 coupled to distal portion 140 of knife block 114 have been moved in the direction of arrow "E" to their advanced position to advance cutting edge 182 of annular knife 116 into cutting ring 42 of anvil assembly 18. In this position, the distal portion of the annular knife 116 is embedded in the cutting ring 42 of the anvil assembly 18.

Fig. 12 and 13 illustrate reload assembly 100 and anvil assembly 18 of stapling apparatus 10 in a fired position as anvil assembly 18 is moved from a clamped position wherein anvil head 30 is in juxtaposed alignment with staple cartridge 118 to an open position wherein anvil head 30 is spaced from staple cartridge 118. In this position, anvil assembly 18 is moved away from tool post 114 in the direction of arrow "F". Because annular knife 116 is embedded in cutting ring 42 of anvil head 30, movement of anvil head 30 in the direction of arrow "F" will cause knife block 114 to move in the direction of arrow "G", as shown in FIG. 12. When any further distal movement of knife block 114 within housing 110 is limited, further distal movement of anvil head 30 relative to knife block 114 in the direction of arrow "H" in fig. 13 will cause engagement portions 184 on the proximal portion of annular knife 116 to exert a force on resilient fingers 172 on the distal tip of knife block 114 to separate annular knife 116 from knife block 114. The cutting edge 182 of annular knife 116 will remain embedded in the cutting ring 42 of cut ring assembly 40 in anvil head 30 of anvil assembly 18 to safely protect the clinician from the cutting edge 182 of annular knife 116.

Fig. 14 and 15 illustrate reload assembly 100 and anvil assembly 18 of stapling apparatus 10 with anvil head 30 of anvil assembly 18 in an inclined position and annular knife 116 embedded in cutting ring 42 of cut ring assembly 40 of anvil assembly 18. Anvil head 30 is urged to the tilted position by a biasing mechanism 50 supported within central rod 32 of anvil assembly 18. For a detailed description of exemplary aspects of the biasing mechanism 50, see, for example, the' 106 patent.

Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is contemplated that elements and features illustrated or described in connection with one exemplary embodiment may be combined with elements and features of another exemplary embodiment without departing from the scope of the present disclosure. Likewise, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims.

Claims

1. A reload assembly comprising:

a housing shell defining a cavity and having a proximal portion and a distal portion;

a staple cartridge supported on the distal portion of the housing shell, the staple cartridge supporting a plurality of staples;

a staple push member movable within the housing housing between an advanced position and a retracted position to eject the plurality of staples from the staple cartridge, the staple push member defining a longitudinal hole;

a blade holder supported within the longitudinal bore of the nail push member, the blade holder having a distal portion defining a first engagement portion, the blade holder capable of retracting and advancing within the housing shell move between locations; and

a knife having a proximal portion and a distal portion, the proximal portion defining a second engagement portion coupled to the first engagement portion to removably secure the knife to the A knife holder, wherein the knife can be decoupled from the first engagement portion of the knife holder after a predetermined force is applied to the knife in a distal direction.

2. The reload assembly of claim 1, wherein the knife is annular.

3. The reload assembly of claim 1, wherein the first engagement portion is defined by a plurality of resilient fingers formed on the distal portion of the tool holder.

4. The reload assembly of claim 3, wherein each of the plurality of resilient fingers defines a concave surface to define an annular recess surrounding the distal portion of the tool holder.

5. The reload assembly of claim 4, wherein the second engagement portion formed on the proximal portion of the knife comprises an annular projection portion received in a position by the blade. within the annular recess defined by the plurality of resilient fingers of the tool holder to removably secure the knife to the tool holder.

6. The reload assembly of claim 5, wherein the second engagement portion is formed on the proximal portion of the knife by inverting the proximal portion of the knife.

7. A suturing device comprising:

an adapter assembly having a distal tip portion;

a reload assembly secured to the distal tip portion of the adapter assembly, the reload assembly comprising:

a blade holder supported within the longitudinal bore of the nail push member, the blade holder having a distal portion defining a first engagement portion, the blade holder capable of advancing in a retracted position and advancing within the housing shell move between locations; and

A knife having a proximal portion and a distal portion, the distal portion defining a cutting edge, the proximal portion defining a second engagement portion coupled to the first engagement portion to removably secure the knife to the knife holder, wherein the knife is decoupled from the first engagement portion of the knife holder after a predetermined force is applied to the knife in a distal direction; and

an anvil assembly movable relative to the staple cartridge between an open position and a clamped position, the anvil assembly including a cutting ring formed of a material penetrable by the knife, wherein when the stapling device When fired, the knife is embedded in the cutting ring, and when the anvil assembly is moved from the clamped position to the open position, after the stapling device is fired, the knife and the The knife holder is separated.

8. The suturing device of claim 7, wherein the knife is annular.

9. The stapling device of claim 8, wherein the first engagement portion is defined by a plurality of resilient fingers formed on the distal portion of the blade holder.

10. The stapling device of claim 9, wherein each of the plurality of resilient fingers defines a concave surface to define an annular recess surrounding the distal portion of the blade holder.

11. The suturing device of claim 10, wherein the second engagement portion formed on the proximal portion of the knife includes an annular protrusion received within the knife by the knife. within the annular recess defined by the plurality of resilient fingers of the holder to removably secure the knife to the knife holder.

12. The stapling device of claim 11, wherein the second engagement portion is formed on the proximal portion of the knife by inverting the proximal portion of the knife.

13. The stapling device of claim 1, wherein the anvil assembly includes an anvil head and a center rod, the anvil head pivotally coupled to the center rod and movable from an operating position to a tilted position .

14. A knife assembly comprising:

a tool holder having a distal portion defining a first engagement portion; and

A knife having a proximal portion and a distal portion, the distal portion defining a cutting edge, the proximal portion defining a second engagement portion coupled to the first engagement portion to connect the A knife is removably secured to the knife holder, wherein the knife can be decoupled from the first engagement portion of the knife holder after a predetermined force is applied to the knife.

15. The knife assembly of claim 14, wherein the knife is annular.

16. The knife assembly of claim 15, wherein the first engagement portion is defined by a plurality of resilient fingers formed on the distal portion of the knife holder.

17. The knife assembly of claim 16, wherein each of the plurality of resilient fingers defines a concave surface to define an annular recess surrounding the distal portion of the knife holder.

18. The knife assembly of claim 17, wherein the second engagement portion formed on the proximal portion of the knife includes an annular raised portion received by the knife within the annular recess defined by the plurality of resilient fingers of the holder to removably secure the knife to the knife holder.

19. The knife assembly of claim 18, wherein the second engagement portion is formed on the proximal portion of the knife by inverting the proximal portion of the knife.